1. Field of the Invention
The invention relates to a device for the stepwise transport of liquid through several flow chambers located in series in terms of flow while utilizing capillary forces, the liquids preferably being sample liquids to be analyzed.
In the most different application fields of analytics and diagnostics, it is required to analyze sample liquids. The assays used therefor sometimes require that the sample liquids are sequentially brought into contact with different reagents. With respect to the automation of such assays, it is advantageous to be able to transport the sample liquid to be analyzed in a stepwise manner.
2. Description of Related Art
In the state of the art, it is basically known to initiate the transport of liquid through a channel and in order to fill a chamber by deaerating the channel and the chamber, respectively, whereby a liquid flow is created. Examples for such selective liquid flow mechanisms are described in International Patent No. 99/46045, International Patent No. 01/64344, U.S. Pat. No. 4,849,340, U.S. Pat. No. 5,230,866, U.S. Pat. No. 5,242,606 and U.S. Pat. No. 5,478,751.
Further, U.S. Pat. No. 3,799,742 describes a fluid system where a liquid flow from a reservoir into the individual chambers is caused by utilizing gravity and the selective deareation of individual chambers connected in series and in parallel. In this known device, a liquid channel extends from a reservoir. Along this liquid channel, several branch channels branch off which end in two chambers connected in series. At the level of the junction of the branch channels to the chambers, vent lines branch off them all of which are closed and can be opened selectively. The afore-described channel system allows for a liquid transport exclusively by the utilization of gravity. As long as all vent holes are closed, the liquid transport from the reservoir is prevented by retaining the liquid by the gas counterpressure. When the chamber of the two chambers per branch channel which is arranged first in flow direction is aerated, liquid from the reservoir can flow into this chamber. By installing a gas-permeable filter that is hydrophobic with respect to the liquid, it is ruled out that the liquid escapes from the vent line of this chamber. Passing into the second chamber arranged downstream is prevented by the fact that this chamber is not deaerated. Only if this chamber is deaerated, liquid enters into the second chamber as well. This known system requires the substantially vertical orientation of the substrate in which the channel system is configured. This restricts the application of the system inasmuch as no liquid transport can be effected when the substrate is in the horizontal state since it lacks the gravity component initiating the liquid flow.